Phd records
https://feeds.library.caltech.edu/people/Gimlett-James-L/Phd.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenWed, 31 Jan 2024 19:07:45 +0000Experimental study of time reversal invariance and atomic final state effects in nuclear transitions
https://resolver.caltech.edu/CaltechTHESIS:10272016-131924862
Authors: {'items': [{'id': 'Gimlett-James-L', 'name': {'family': 'Gimlett', 'given': 'James L.'}, 'show_email': 'NO'}]}
Year: 1980
DOI: 10.7907/n7sw-jy41
Experiments have been performed to test time reversal invariance
in nuclei using gamma transitions of oriented <sup>191</sup>Ir and <sup>131</sup>Xe. The
phase angle η associated with the imaginary part of the ratio of reduced
matrix elements of the gamma transition was measured through observation
of the angular distribution of the linear polarization from
oriented nuclei. Interaction of the gamma ray with the atomic electron
cloud can cause an additional phase shift ξ which is indistinguishable
from the time-reversal phase η. Such an atomic final state effect has
been observed for the 129 keV transition in <sup>191</sup>Ir. Nuclear orientation
was achieved with a large magnetic field (the hyperfine field of Ir in
iron) and low temperature (20 to 30 mK obtained with a dilution refrigerator).
A Compton polarimeter was used to measure linear polarization
of the E2-Ml gamma ray. The matrix-element ratio was found to have an
imaginary part corresponding to a phase angle (η+ξ) = (-4.8 ± 0.2) x 10<sup>-3</sup>.
This measurement is in agreement with the most recent final state calculations
which give ξ = (-4.3 ± 0.4) x 10<sup>-3</sup>. A limit |η| < 10<sup>-3</sup> is
deduced for the time-reversal phase. In another experiment a phase angle
η = (-1.2 ± 1.1) x 10<sup>-3</sup> was measured for the E2-Ml 364 keV transition in
<sup>131</sup>Xe, for which atomic final state effects are small. Both measurements
are consistent with time reversal invariance.https://thesis.library.caltech.edu/id/eprint/9961